Revenue from Contracts with Customers - Segment Information (Details) - segment	3 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Number of reportable segments	2	2
Number of reporting units	5	5
Brooks Semiconductor Solutions Group
Segment Reporting Information [Line Items]
Number of reporting units	3	3
Brooks Life Sciences
Segment Reporting Information [Line Items]
Number of reporting units	2	2